Microcystis aeruginosa is a common microalgae in nature. It is also the dominant algae species to form freshwater blooms. Water bloom will do harm to water environment, so this paper studies the growth law of Microcystis aeruginosa. Single factor experiment and orthogonal experiment were carried out by changing the influencing factors such as photoperiod, initial dosage and initial pH. The results showed that within a certain range, the larger the photoperiod, the larger the initial dosage, the higher the initial pH, the better the growth of Microcystis aeruginosa and the greater the increase of pH value. This study is to deepen the understanding of the growth law of Microcystis aeruginosa. It provides a scientific basis for controlling the growth of Microcystis aeruginosa.